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Crop Production &
Soil Management Series
Field Crop Fertilizer Recommendations
For Alaska Vegetables
Most cool-season vegetables can be successfully grown
outdoors in Alaska. Many will benefit from cultural
practices designed to lengthen the growing season. These
include transplanting greenhouse-grown seedlings rather
than seeding directly in the field, growing plants on
plastic mulches and using plastic row covers. Most may
be successfully produced by direct-seeding in bare soil;
however, yields may be lower. The recommendations in
this publication are general in nature and should apply regardless of the cultural practices used in vegetable
production. Warm-season vegetables such as tomatoes
and peppers may be reliably produced in much of Alaska
only in a greenhouse. These crops are not included in this
publication.
Relatively little fertility research has been conducted on
vegetables in Alaska. Most previous Alaska research has
FGV-00643
been conducted on lettuce; the information provided for
other vegetable crops is adapted from research and recommendations from other states.
Soil Acidity
The preferred soil pH ranges for vegetable crops are listed
in Table 1. These ranges are for mineral soils only. Organic soils (peats and mucks) may be maintained at lower
pH levels and are rarely limed. In mineral soils, the soil
pH should be adjusted to approximately the middle of the
recommended range for best performance. Various liming materials may be used to raise pH; elemental sulfur
may be used to reduce it.
Nitrogen source is not considered to be critical for most
vegetables, as long as management is suitable for the chosen fertilizer source (for example, urea should be incor-
Table 1. Vegetable crop soil pH ranges.
Vegetable
Optimum pH range
Beets
5.8 – 8.0
Broccoli
6.0 – 7.5
Brussels sprouts
6.0 – 7.5
Cabbage
5.8 – 8.0
Carrots
5.3 – 6.8
Cauliflower
5.8 – 7.0
Celery
5.8 – 7.0
Chinese cabbage
6.0 – 7.5
Lettuce
5.8 – 7.0
Peas
5.8 – 6.8
Radishes
5.8 – 7.0
Squash
5.3 – 7.5
Turnips
6.0 – 7.0
Source: Western Fertilizer Handbook: Horticulture Edition by the Soil Improvement Committee, California Fertilizer Association.
Table 2. Recommended nitrogen application rates for vegetables in Alaska
Vegetablelb/a
Beets
75 – 100
Broccoli
100 – 150
Cabbage
100 – 150
Carrots
60 – 100
Cauliflower
100 – 150
Celery
100 – 150
Cucumbers
75 – 100
Lettuce
100 – 125
Peas
25 – 50
Radishes
50
Squash
50 – 100
porated rather than applied to the soil surface). If organic
sources of N are used, release rates must be rapid enough
to provide adequate N for the growing plant.
nium phosphates or similar materials. If materials with
slowly available P, such as rock phosphates, or some other
organic sources are used, application rates will generally
have to be adjusted upward. The recommended application rates are for the soil test listed above each recommendation. All recommendations are in pounds of P2O5
per acre. For soil test values between those listed, interpolate from the values in Table 3. For example, a Kenai soil
testing 20 ppm P (half-way between the very low and low
categories) would require about 175 pounds of P2O5 per
acre (half-way between 150 and 200).
Leguminous crops such as beans and peas can fix atmospheric N if they are inoculated with proper bacteria.
Inoculum should be applied to legume seeds prior to
planting unless the seed has been pre-inoculated. Follow supplier’s recommendations for inoculum rate and
handling procedures.
Phosphorus
Phosphorus (P) utilization is affected by soil conditions,
including both the past fertilization history of the soil as
reflected by the soil test P level and by soil minerology.
Generally, soils testing high in P require a lower rate of
fertilization than those with a low test level. Also, soils
with high capacities for fixing or immobilizing phosphorus may require higher P application rates to overcome
this fixing capacity. In non-alkaline soils, P immobilization increases as soil pH drops. Additionally, there
are two types of soils in Alaska that have high P fixing
capacity: the volcanic ash soils (including the Kachemak,
Kashwitna, Naptowne, Rabideux and Tustemena series)
and the alkaline soils of Interior Alaska.
Phosphorus fertilizers are usually applied at or before the
time of planting. Phosphorus may be broadcast uniformly and incorporated into the soil or may be banded
at planting. Fertilizer bands should not be in contact
with the vegetable seed or seedling, but should be placed
two inches below and two inches to the side of the seed
or seedling. If fertilizer is banded, the rate of application
may be adjusted slightly downward (decrease by no more
than 25 percent).
Potassium
Both potassium chloride and potassium sulfate provide an adequate source of K for vegetables. Potassium
chloride is generally less expensive, although potassium
sulfate may be preferred for the fertilization of salt-sensitive crops or when salt-sensitive crops are included in a
rotation (see Table 4).
Phosphorus availability is also reduced in cold soils,
which are usually found early in the growing season.
Therefore, it is important to supply enough P to plants
during this critical period. This may be achieved through
application of starter fertilizer at the time of planting.
Potassium may be applied prior to or at planting. Either
band or broadcast applications of K should generally
provide satisfactory results, although salt-sensitive crops
may be adversely affected by banded fertilizers. High salt
levels can burn root tissues, inhibit root growth and slow
The recommended rates in Table 3 are based on the use of
highly soluble P sources such as triple super phosphate,
ordinary or single super phosphate, mono- or diammo2
plant development. Follow the recommended K application rates in Table 5.
lacking, they may be broadcast or band applied before or
at the time of planting according to Table 6. If the soil pH
is too low, Ca can be supplied by applying calcitic lime, or
Ca and Mg can be provided with application of dolomitic
lime.
Secondary and Micronutrients
Deficiencies of secondary nutrients (calcium (Ca), magnesium (Mg) and sulfur (S)) are uncommon. They are
most likely to occur on well-drained sandy soils. Adequate S will almost always be provided if sulfate salts of
potassium or nitrogen are used. Calcium and Mg levels
usually will be adequate if the soil pH is maintained in
the proper range. If secondary nutrients are found to be
Micronutrient nutrition usually is not a problem in
vegetable production. However, copper (Cu), iron (Fe),
manganese (Mn) and zinc (Zn) may become deficient
if the soil pH is high (pH of 7.0 or above). In this case
the best remedy is to lower the soil pH by addition of
Table 3. Recommended phosphorus application rates for vegetables1
Soil Series
Soil Test
Category 2
Cohoe, Island, Kenai,
Naptowne, Soldotna,
Tustamena
soil test (ppm)
Beluga, Kachemak,
Mutnala
soil test (ppm)
Very
Low
Very
LowMedium High
High
4
35
66
97
128
200
150
100
50
03
4
55
107
158
209
200
150
100
50
03
4
58
111
165
219
lb P2O5 to add/a
200
150
100
50
03
Bodenberg, Doone,
Knik, Matanuska,
Niklason, Susitna,
soil test (ppm)
43
70
96
123
150
lb P2O5 to add/a
200
150
100
50
03
Beales, Chena,
Fairbanks, Gilmore,
Goldstream, Nenana,
Steese
soil test (ppm)
6
61
115
170
225
200
150
100
50
03
Jarvis, Richardson,
Salchaket, Tanana,
Volkmar
soil test (ppm)
6
39
72
106
139
200
150
100
50
03
Chulitna, Flathorn,
Homestead, Nancy,
Kashwitna, Schrock,
Rabideaux, Whitsol,
Talkeetna
lb P2O5 to add/a
lb P2O5 to add/a
soil test (ppm)
lb P2O5 to add/a
lb P2O5 to add/a
From Michaelson & Ping, 1989.
1
2
Mehlich 3 extraction.
3
When soil phosphorus tests are at the very high level and above, it is generally recommended that a small amount of phosphorus
(about 50 lb P2O5/a) be applied as a starter fertilizer to provide adequate nutrition in cool soils.
3
Table 4. Salt-sensitivity of vegetable crops
VegetableSalt-Sensitivity
Beets
Broccoli
moderately tolerant
Cabbage
moderately tolerant
Carrots
moderately tolerant
Cauliflower
moderately tolerant
highly tolerant
Celery
sensitive
Cucumbers
moderately tolerant
Lettuce
moderately tolerant
Peas
moderately tolerant
Radishes
sensitive
Squash
moderately tolerant
Source: Diagnosis and Improvement of Saline and Alkali Soils. 1954. USDA Agriculture Handbook Number 60.
elemental sulfur. If required, the micronutrients may be
added at the rates suggested in Table 7 with the following
exceptions. Beets, cauliflower and celery have very high
boron (B) requirements; add one pound/acre every year
when growing these crops. If B deficiency is suspected,
soil and plant analyses are recommended. Also, molybdenum (Mo) deficiencies are fairly common in cole crops
(broccoli, cauliflower, cabbage) and may be indicated by
elongation of the leaf base. Apply Mo according to Table
7. Please note that over-application of micronutrients can
result in plant damage.
If a field contains both healthy and unhealthy plants,
leaf samples can be collected from both the healthy and
unhealthy plants, making sure that the same plant part is
taken in both cases. The healthy plant can then be used as
the standard value to compare the unhealthy plant against.
Plant tissue samples should be taken from plants representative of the sampling area. Dead or damaged plants,
those with insect or disease problems, those at the end
of rows or in edge rows or plants that differ significantly
from those in the rest of the planting should not be
sampled. Plants that have been recently sprayed with
foliar fertilizers should be avoided. It is important that
at least the recommended number of plants are sampled
to ensure that a representative sample is obtained. If the
recommended sample size is 25 mature leaves, all leaves
should be taken from separate plants. In addition, the
sampled plants should be randomly selected from a field,
not concentrated in one area.
Tissue Analysis
Problems suspected to be caused by lack of nutrients
often can be confirmed by plant tissue analysis. Plants
of various ages differ in nutrient content; different plant
parts also contain varying levels of plant nutrients. Therefore, it is critical that the plant structure collected is one
for which standard values are known. In small plants,
the whole above-ground portion of the plant is usually
sampled. In older plants, the most common method of
sampling is to collect the youngest fully mature (grown
to its full size) leaf or to take the petioles (leaf stems)
associated with those leaves. For those plants requiring
leaf sampling, the petiole is usually not included. Petioles
are often used for sampling soluble nutrients (nitrate,
phosphate and potassium) because this is the conducting
tissue where nutrients travel from the stem to the leaf and
may provide a more sensitive test for these nutrients than
leaf analysis. The recommended plant part for sampling
various vegetable crops is given in Table 8.
Try to sample clean leaves. Leaves should be washed only
if they are to analyzed for iron or aluminum. Washing
should be done quickly in a mild (2%) detergent solution
if required. Fresh tissue samples must be dried rapidly at
150 to 175°F until all water is removed. Drying at higher
temperatures may destroy plant tissues; drying at lower
temperatures will not stop biological activity. Tissue
samples will dry best in open containers, cloth bags, or
opened paper bags. Samples should be dried immediately
following sampling. If this is not possible, samples may be
refrigerated for short periods of time prior to drying.
4
Table 5. Recommended potassium application rates for vegetables
Soil Test level 1 (ppm)
Recommended Application Rate
——— lb K2O/a ———
0 – 75
180
76 – 150
120
151 – 300
60
Above 301
0
1
Mehlich 3 extraction.
Table 6. Recommended secondary nutrient application rates and sources for vegetables
Nutrient
1
Sources
Recommended Application Rates
Calcium
gypsum (CaSO4)
100 – 500 lb Ca/a if broadcast;
20 – 50 lb Ca/a if banded
Magnesium epsom salts or kieserite (MgSO4), sulfate of
magnesium potash or sulpomag (K2SO4 • 2MgSO4)
50 – 100 lb Mg/a if broadcast;
10 – 20 lb Mg/a if banded
Sulfur
25 – 100 lb S/a
elemental sulfur1, epsom salts, gypsum, sulpomag, ammonium sulfate (NH4)2SO4,
potassium sulfate (K2SO4)
Elemental S should never be banded. As a broadcast treatment, 1,000 lb of elemental S/a generally will reduce soil pH between 1
to 2 units.
Table 7. Recommended micronutrient application rates and sources for vegetables
Nutrient
Sources
Recommended Application Rates
Boron
borax, solubor
1 lb B/a
Copper
copper chelates
1 – 2 lb Cu/a banded; or 4-8 lb Cu/a broadcast
Iron
iron sulfate (FeSO4)
2.5 – 7.5 lb Fe as FeSO4/a in 20 gallons water applied foliarly
Manganese
manganese chelates,
manganese sulfate (MnSO4)
3 lb Mn as MnSO4/a or 0.5 lb Mn/a as Mn chelate
banded; or 1 lb Mn in 20 gallons water applied foliarly
Molybdenum
sodium or ammonium
molybdate
0.5 – 5 oz Mo/a broadcast; or 0.5 – 1.0 oz
Mo/a in 20 gallons water applied foliarly
Zinc
zinc chelates or
zinc sulfate (ZnSO4)
0.5 – 1.0 lb Zn as chelate or 2-4 lb Zn/a as ZnSO4 banded; or
1 – 2 lb Zn as chelate or 4-8 lb Zn/a as ZnSO4 broadcast; or
0.15 lb Zn as chelate or 1 lb Zn/a as ZnSO4 applied foliarly in
20 gallons water
5
Carling, D.E., G.J. Michaelson and C.L. Ping. 1988. The
Effects of Nitrogen Fertilization Rates on Yields of
Transplanted and Direct-Seeded Head Lettuce. University of Alaska Fairbanks, Agricultural and Forestry
Experiment Station Research Progress Report 6.
Nutritional status of the sampled plants can be evaluated by comparison with appropriate nutrient sufficiency
ranges (Tables 9 and 10). It will often be impossible to
correct nutritional problems in the same growing season
the samples were collected. However, nutritional information from tissue analyses should be used to adjust fertility
practices in subsequent years.
Dow, A.I. 1980. Critical Nutrient Ranges in Northwest
Crops. Western Regional Extension Publication No.
43.
References
Geraldson, C.M. and K.B. Tyler. 1990. "Plant Analysis as
an Aid to Fertilizing Vegetables." In Soil Testing and
Plant Analysis., R.L. Westerman, ed., Soil Science
Society of America, Madison, WI.
Information in this document is derived from original
research and from the following publications.
Carling, D.E., G.J. Michaelson, C.L. Ping and G.A. Mitchell. 1987. The Effects of Nitrogen Fertilization Rates on
Head Lettuce Yields. University of Alaska Fairbanks,
Agricultural and Forestry Experiment Station Research Progress Report 3.
Garrison, S.A. 1987. Commercial Vegetable Production
Recommendations. Rutgers, The State University of
New Jersey. Rutgers Cooperative Extension Service
Publication 8001C.
Table 8. Recommended plant part and stage of growth for selected vegetables
Crop
Number of
Plants Sampled
Plant Part
Stage of Growth
Beets 20YML1
at maturity
Broccoli
12
YML or midrib of YML
at heading
Brussels sprouts
12
YML or midrib of YML
at maturity
Cabbage
15
whole tops2
2 – 6 weeks old
Cabbage
12
wrapper leaf
2 – 3 months old
Carrot
15
YML or petiole of YML
mid-season
Carrot
15
oldest leaf
at maturity
Cauliflower
12
YML or midrib of YML
at heading
Celery
12
YML or petiole of YML
half-grown
Chinese cabbage
12
first fully developed leaf
or midrib of YML
8-leaf stage
Chinese cabbage
12
rirst fully developed leaf
or midrib of YML
at maturity
Romaine Lettuce
12
wrapper leaf
at maturity
Head Lettuce
12
wrapper leaf or midrib
of wrapper leaf
heads half size
Turnip
12
YML
mid-growth
1
YML — youngest mature (fully expanded) leaf.
2
Whole tops are the entire above-ground portion of plants.
6
Table 9. Nutrient sufficiency ranges for selected vegetables1
Nutrient
Beets
Broccoli
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Sulfur
BrusselsCabbage Cabbage
sprouts
2-6 wks
2-3 months
——————————————— % ———————————————
4.00 – 5.50
3.20 – 5.50
2.20 – 5.50
3.00 – 5.00
3.00 – 5.00
0.25 – 0.50
0.30 – 0.75
0.26 – 0.75
0.35 – 0.75
0.30 – 0.75
2.00 – 4.50
2.00 – 4.00
2.00 – 4.00
3.50 – 6.00
3.00 – 5.00
2.50 – 3.50
1.00 – 2.50
0.30 – 2.50
3.00 – 4.50
1.10 – 3.50
0.30 – 1.00
0.23 – 0.75
0.23 – 0.75
0.50 – 2.00
0.24 – 0.75
————
0.30 – 0.75
0.30 – 0.75
————
0.30 – 0.75
—————————————— ppm ——————————————
Boron
Copper
Iron
Manganese
Molybdenum
Zinc
Nutrient
30 – 85
5 – 15
50 – 200
50 – 250
————
15 – 200
30 – 100
5 – 15
70 – 300
25 – 200
————
35 – 200
30 – 100
5 – 15
60 – 300
25 – 200
0.25 – 1.00
25- – .00
25 – 75
5 – 15
30 – 200
25 – 200
0.40 – 0.70
20 – 200
CarrotsCarrots
mid-season
mature
Cauliflower
Celery
Chinese
Cabbage
——————————————— % ———————————————
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
1.80 – 3.50
0.20 – 0.50
2.00 – 4.30
1.40 – 3.00
0.30 – 0.53
3.00 – 3.50
0.20 – 0.40
2.90 – 3.50
1.00 – 2.00
0.25 – 0.60
3.00 – 4.50
0.33 – 0.80
2.60 – 4.20
0.70 – 3.50
0.24 – 0.50
2.50 – 3.50
0.30 – 0.50
4.00 – 7.00
0.60 – 3.00
0.20 – 0.50
4.50 – 5.50
0.50 – 0.60
7.50 – 9.00
3.00 – 5.50
0.35 – 0.50
—————————————— ppm ——————————————
Boron
Copper
Iron
Manganese
Molybdenum
Zinc
29 – 100
4.5 – 15
50 – 300
60 – 200
0.5 – 1.5
20 – 250
30 – 75
5 – 15
50 – 300
60 – 200
0.5 – 1.4
20 – 250
30 – 100
4 – 15
30 – 200
25 – 250
0.5 – 0.8
20 – 250
RomaineHead
Nutrient LettuceLettuce
Turnip
———————— % ————————
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
3.50 – 4.50
0.45 – 0.80
5.50 – 6.20
2.00 – 2.80
0.60 – 0.80
3.50 – 5.00
0.40 – 0.60
6.00 – 9.60
1.40 – 2.25
0.36 – 0.70
3.50 – 5.00
0.33 – 0.60
3.50 – 5.00
1.50 – 4.00
0.30 – 1.00
———————— ppm ————————
Boron
Copper
Iron
Manganese
Zinc
25 – 60
5 – 25
40 – 100
11 – 250
20 – 250
1
25- – 5 – 15
30 – 200
50 – 200
————
25 – 200
23 – 50
7 – 25
50 – 175
20 – 250
25 – 250
30 – 100
6 – 25
40 – 300
40 – 250
20 – 250
Standard nutrient levels are for plant parts and growth stages specified in Table 8.
7
30 – 50
5 – 8
20 – 40
200 – 300
————
20 – 50
23 – 75
5 – 25
31 – 200
25 – 200
————
30 – 200
Table 10. Sufficiency levels for nitrate, phosphate and potassium in petioles and leaf midribs of vegetables
Crop
Stage of
Growth
Plant Part
Broccoli
mid-growth
first buds
midrib of YML1>9,000 >4,000
>7,000
>4,000
>5.0
>4.0
Brussels sprouts
mid-growth
late growth
midrib of YML
>9,000
>7,000
>3,500
>3,000
>5.0
>4.0
Carrot
mid-growth
petiole of YML
>10,000
>4,000
>6.0
Cauliflower
head-forming
midrib of YML
>9,000
>5,000
>4.0
Celery
mid-growth
petiole of YML
near mature
>9,000
>6,000
>5,000
>3,000
>6.0
>5.0
Chinese cabbage
heading
midrib of
wrapper leaf
>9,000
>3,500
>4.0
Head lettuce
heading
harvest
midrib of
wrapper leaf
>8,000
>6,000
>4,000
>2,500
>4.0
>2.5
1
Nitrate-N
(ppm)
Phosphate-P
(ppm)
Potassium
(%)
YML — youngest mature (fully expanded) leaf.
Jones, J.B. Jr., B. Wolf and H.A. Mills. 1991. Plant Analysis
Handbook. Athens, GA : Micro-Macro Publishing,
Inc.
Western Fertilizer Handbook: Horticulture Edition. 1990.
Soil Improvement Committee, California Fertilizer
Association. Danville, IL: Interstate Publishers, Inc.
Kelling, K.A., P.E. Fixen, E.E. Schulte, E.A. Liegal and
C.R. Simson. 1976. Soil Test Recommendations for
Field, Vegetable and Fruit Crops. University of Wisconsin Cooperative Extension Service Publication
A2809.
Turner, D.O., A.R. Halvorson and M.L. Jarmin. 1974.
Fertilizing Guide: Cabbage, Broccoli, Cauliflower and
Brussels Sprouts for Western Washington. Washington
State University Cooperative Extension Service Pub.
FG-47.
Michaelson, G.J. and C.L. Ping. 1989. Interpretation of the
Phosphorus Soil Test for Alaska Agricultural Soils. University of Alaska Fairbanks, Agricultural and Forestry
Experiment Station Circular 66.
Turner, D.O., W.C. Anderson, A.R. Halvorson and M.L.
Jarmin. 1979. Fertilizing Guide: Carrots for Western
Washington. Washington State University Cooperative Extension Service Publication FG-51.
Sanchez, C.A., H.W. Burdine and V.L. Guzman. 1989.
"Soil Testing and Plant Analysis as Guides for the
Fertilization of Celery on Histosols." Soil and Crop
Science Society of Florida Proc. 49:69-72.
United States Salinity Laboratory Staff. 1954. Diagnosis
and Improvement of Saline and Alkali Soils. USDA
Agriculture Handbook Number 60.
Sanchez, C.A., G.H. Snyder and H.W. Burdine. 1991.
"DRIS Evaluation of the Nutritional Status of Crisphead Lettuce." HortScience, 23:274-276.
Walworth, J.L., D.E. Carling and G.J. Michaelson. 1992.
"Nitrogen Sources and Rates for Direct-Seeded and
Transplanted Head Lettuce." HortScience, 27: 228230.
www.uaf.edu/ces or 1-877-520-5211
Steven Seefeldt, Extension Faculty, Agriculture and Horticulture
Published by the University of Alaska Fairbanks Cooperative Extension Service in cooperation with the United States Department of Agriculture. The University of Alaska Fairbanks is an affirmative action/equal opportunity employer and educational institution.
©2014 University of Alaska Fairbanks.
3-92/JW/11-14
Reviewed October 2012